1 files changed, 2 insertions, 1 deletions

diff --git a/src/firejail/main.c b/src/firejail/main.c
index 94000d917..569fc7add 100644
--- a/src/firejail/main.c
+++ b/src/firejail/main.c
@@ -161,7 +161,8 @@ static inline int read_pid(char *str, pid_t *pid) {
                 || (errno != 0 && pidtmp == 0)) {
                 return 1;
         }
-        if (endptr == str) {
+        // endptr points to '\0' char in str if the entire string is valid
+        if (endptr == NULL || endptr[0]!='\0') {
                 return 1;
         }
         *pid = (pid_t)pidtmp;